Exploration of underwater New Mexico cave turns deadly

A deep-water exploration of the maze-like passageways underneath a well-known swimming hole in New Mexico turned deadly when an experienced California diver helping with the effort drowned.

Authorities said Thursday the investigation suggests 43-year-old Shane Thompson's death below the Blue Hole, a tourist destination in the community of Santa Rosa, was an accidental drowning.

Police Chief Jude Gallegos said Thompson was among 10 or so people from the ADM Exploration Foundation who were at Blue Hole for a multiple-day exploration. The group had been working on surveying the underwater cave system since 2013.

Thompson dove into Blue Hole on March 26 with another experienced diver, Mike Young, Gallegos said. They planned to have Young enter part of the cave system while Thompson stayed outside in a safety role.

Instead of staying outside, Thompson entered. "Apparently something went horribly wrong, and he started to panic," the chief said.

The divers were about 160 feet below the surface when the incident happened.

The Blue Hole has been an attraction in New Mexico for centuries. The artesian spring, tucked into a rock outcropping, pumps out about 3,000 gallons per minute, resulting in crystal-clear conditions that have attracted divers from around the world. Legend has it that outlaw Billy the Kid would take a dip at the swimming hole before heading into Santa Rosa.

Authorities installed a grate at the bottom of the bell-shaped swimming hole to prevent untrained divers from gaining access to an underwater cave system that Gallegos said resembles "a maze — kind of looks like intestines."

Thompson's group obtained permission to explore the passageways, but it is now off-limits to the public after the drowning.

"The cave system below is walled out. That means there is no cave passage left to explore," said Curt Bowen, president of the exploration foundation. "We mapped everything we could fit through, and it ended in a tight rock breakdown at a depth of 194 feet."

It still was unclear Thursday what went wrong. It could be weeks before autopsy results are available, the state Office of the Medical Investigator said.

Family members said Thursday they were struggling with Thompson's death, but they acknowledged that diving was what he loved to do and that he had earned numerous certifications during his lifetime.

A Navy veteran, Thompson began diving at a young age while growing up in the Florida Keys. After earning his first certification, he went to work for an underwater construction company and later started numerous diving businesses that focused on everything from boat maintenance to salvage work and training.

Last year, Thompson rediscovered the wreckage of the B-36 "Peacemaker" bomber that had crashed in 1952 near Mission Beach. A video posted by Thompson's San Diego-based Advanced Underwater Training business shows his flashlight scanning the engines and other corroded pieces of the plane as he makes his way through the darkness more than 250 feet below the surface.

In the coming weeks, Bowen said he plans to complete a three-dimensional map that will illustrate the entire Blue Hole system.

The caves have been sealed off since 1976, when two divers in training died after getting separated from their classmates. New Mexico State Police divers quickly found one of the bodies, but it took several weeks to find the other. In the process, police divers made a crude map of some of the unexplored passages.

At that time, one of the divers descended and found himself at the edge of an underwater cliff. His powerful flashlight wasn't enough to see the cave wall across from him or the bottom, sparking only more curiosity.

In 2013, divers with the ADM Exploration Foundation attempted an expedition, but they had little success getting past the tons of rock the city dumped onto the grate to keep people out.

Divers with the foundation returned in 2015 for more excavation work and were able to reach a depth of 160 feet. They returned in late March to continue surveying.

Divers from around the region flock to Blue Hole for fun and certification, as it's one of the best diving spots in the American Southwest. About 8,000 dive permits are sold each year.

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Montoya Bryan reported from Albuquerque, New Mexico, and Davenport from Phoenix.